The U.S. spends more on health care than any other country. Here’s what we’re buying.

American health-care spending, measured in trillions of dollars, boggles the mind. Last year, we spent $3.2 trillion on health care — a number so large that it can be difficult to grasp its scale.

A new study published in the Journal of the American Medical Association reveals what patients and their insurers are spending that money on, breaking it down by 155 diseases, patient age and category — such as pharmaceuticals or hospitalizations. Among its findings:

The analysis provides some insight into what’s driving one particularly large statistic: Within a decade, close to a fifth of the American economy will consist of health care.

“It’s important we have a complete landscape when thinking about ways to make the health care system more efficient,” said Joseph Dieleman, an assistant professor at the Institute for Health Metrics and Evaluation at the University of Washington who led the work.

The data show that the primary drivers of health-care spending vary considerably. For example, more than half of diabetes care is spending on drugs, while only about 4 percent of spending on low back and neck pain was on pharmaceuticals. Generally, more spending is done on elderly people, but about 70 percent of the spending on low back and neck pain was on working-age adults. Such insights provide a way to find the drivers of growth in health-care spending and to launch strategies to control it.

“Data like this continues to draw attention to the fact a lot of these proposals being discussed about controlling health-care costs really don’t address the underlying issue, which is rising disease prevalence,” said Ken Thorpe, a professor of health policy at Emory University who was not involved in the study but has done similar research. “You see this rise in chronic disease spending — much of it is potentially preventable.”

Most of the discussion of health care in America has focused on access to insurance, but the spending breakdown shows that the biggest opportunities may come in preventing disease.